1. Field of the Invention
This invention is directed to an encoding and modulation technique for communication systems, and more particularly to a duobinary coding and modulation technique for optical transmission systems.
2. Background Art
In the long haul, high bit rate optical fiber telecommunications, appropriate coding and modulation of the signal for transmission are essential. As the demand grows for bit rates of 10 Gb/s or more, certain inherent limitations of the transmitter and the fiber come into effect. One of these limitations is the chromatic dispersion, which can be relaxed if modulation bandwidth of the optical signal is reduced.